The present invention relates to image forming apparatuses having a unit that can detect when a device that monitors the temperature of a central processing unit (CPU), a regulator, or the like that emits heat or when a cooling fan that cools the CPU or the like fails.
The amount of heat a control unit, such as a CPU that controls an image forming apparatus, or a regulator emits increases as a utilization of the control unit increases, such as when performing multiple processes at the same time. Therefore, the cooling fan is generally provided for the apparatus, or a heat sink is generally attached to the CPU in order to cool the CPU.
Additionally, as the temperature of a heat roller in a fixing device increases, the surrounding temperature also increases. Therefore, a cooling fan is generally provided to reduce the temperature.
To reduce power consumption, the fan is only used when the utilization of the CPU becomes greater during a printing operation of the image forming apparatus. The fan is not used when the device is in a power saving mode, such as in a sleep mode. The same applies to cooling due to the heat roller.
However, with the foregoing method of uniformly switching on the cooling fan in the printing mode and off in the power saving mode, the cooling fan is not necessarily switched on or off based on the actual temperature of the CPU.
Therefore, the cooling fan is running even when the temperature of the CPU, or the like, has not greatly increased, such as when a printing operation is just or only recently started. Thus, the power consumption may increase even more.
In order to avoid unnecessary power consumption, it is preferable to detect the actual temperature of the CPU, the regulator, the heat roller in the fixing device, or the like and to run the cooling fan based on the detected temperature.
Therefore a thermochromic member that changes color according to temperature can be attached to or near a CPU, a regulator, a heat roller, or the like. An optical sensor, such as a charge-coupled device (CCD) camera, is used to detect a change in the color of the thermochromic member, and a cooling fan runs based on the signal detected by the optical sensor.
Therefore, the cooling fan will run based on the actual temperature of the CPU, the regulator, the heat roller, or the like. The cooling fan will not unnecessarily run when the temperature is not sufficiently high. Therefore, this technique can reduce power consumption.
However, because this technique uses a thermochromic member and optical sensor, although no issues typically occur as long as these members and/or the cooling fan is operating normally, if a failure occurs in any of these members, the cooling fan cannot run normally.